Host plant resistance against aphids in Capsicum
Aphids are a major problem in pepper cultivation. Not only do they cause direct damage by feeding, which results in wilting, defoliation and fruit loss, they also cause damage indirectly by the viruses they transmit. Chemical control is widely used. However, due to environmental concerns there are more and more restrictions on the use of these compounds (especially neonicotinoids) and alternatives are needed. One such alternative is host plant resistance. Several aphids can cause problems in pepper cultivation. Of these the green peach aphid (Myzus persicae) and the foxglove aphid (Aulacorthum solani) are the most important in paprika cultivation in the Netherlands and are the focus of this proposal. Over the past years WUR has identified a good source of resistance against the green peach aphid in Capsicum baccatum and characterized its mode of action. One major resistance QTL, containing receptor like kinase genes (RLKs), was identified in a C. baccatum cross. However, recently we found out that introduction of this QTL in Capsicum annuum, did not result in a resistant phenotype. Most likely this means that an additional factor from C. baccatum is needed to get the resistance to work in C. annuum. In this project we want to identify this factor(s). In addition we want to identity resistance against the foxglove aphid and make it available for use in breeding.
The goals of this project are to elucidate which factor, in combination with the already identified RLKs is needed to get the M. persicae resistance to work in C. annuum. Furthermore, the project will identify novel sources of resistance against A. solani, study the genetics of the resistance and characterize the resistance mechanism. Information on the genetics and mechanisms of the resistance to both aphid species, will allow pepper growers to be less dependent on chemical insecticides by creating the scientific basis for the development of aphid resistant varieties.
The project contributes to the mission of the ministry of agriculture by making agriculture less dependent on chemical crop protection (pesticides) by developing robust, resilient varieties that have an intrinsic resistance against pests, in this case aphids. Such varieties are expected to allow growers to comply with the societal demands for sustainable food production. The varieties are produced through breeding in which genetic diversity present in the crop or its wild relatives is used for the improvement.
1. Identification of a yet unknown novel factor that will allow the previously identified aphid resistance QTL to function in C. annuum, including QTL mapping to identify markers that will tag the factor.
2. Information on M. persicae diversity and virulence in the major pepper growing areas of Europe.
3. Identification of a strong resistance source against the foxglove aphid.
4. QTL mapping and identification of markers to introduce the resistance in breeding programs.
5. Information on the foxglove resistance mechanism.
6. Plant material with improved resistance characteristics
7. A PhD thesis and papers in scientific journals